Thermal powerplants that produce electricity generally comprise a turbine powered by fuel, such as fuel oil, and can comprise several combustion chambers. The performance of a powerplant can deteriorate over time for various reasons. In the first place, the aging of the facility itself can result in the deterioration of powerplant performance. Corrosion can also influence thermal powerplant performance. Additionally, the fouling of the compressor and, in particular, the stages of the turbine can have a relatively significant impact on performance of the powerplant. The fouling of the compressor may be particularly liable for causing a reduction in the usable cross-section of the turbine and a deterioration of its aerodynamic characteristics.
The type of fuel oil used has a relatively significant impact on the fouling of the turbine, particularly of its first stages. During combustion of heavy fuel oil, this fouling phenomenon is exacerbated such that the turbine stages are cleaned on a regular basis. Cleaning can be carried out when the machine is shut down by injecting water combined with a detergent onto the surfaces of the turbine stages. Another method is to perform the cleaning when the machine is in operation by injecting an abrasive product into the combustion chambers that is then carried by the hot gases through the turbine stages. A product is chosen that will be destroyed by combustion, releasing nothing but smoke that is evacuated by the exhaust gases of the turbine. The injection generally consists of using pressurized air, for example at 26 bars, and at a temperature of about 200° C., and is extracted as it is discharged from the turbine compressor.
Cleaning performed during operation of the machine is generally termed “on-line” cleaning. A specific module is used to load the abrasive product into a tank, place the tank under pressure and convey the product to the different combustion chambers. Conveying of the product may be done sequentially in order to avoid disturbing the combustion and ensure that the chambers are fed an identical quantity of product.